Preheat the oven to 325 degrees F.
Beat the eggs until light in color. Beat in the sugar until just combined. Add the cocoa, flour, melted butter and vanilla extract. Mix gently until well combined.
Pour the batter into 4 large ramekins. Set the ramekins into a larger pan halfway full of water.
Bake until the upper crust is crispy and the rest of the batter is firm but not set, 40 to 50 minutes. If you pull it out of the oven and have second thoughts, stick it back in for 10 more minutes.
Serve with sweetened whipped cream or vanilla ice cream.
The important thing is that it should NOT be completely set through like a brownie.